The purpose of this study is the examination for the effect of the voluntary exercise and some calcium (Ca) sources on the prevention of osteoporosis. In this study, bone histomorphometry was determined using the IPAP system, which is the Image Processor for Analytical Pathology, and bone mineral density (BMD) and Bone strength were also measured.In 1996, we studied the effect of the exercise an energy intake on bone metabolism using the young rats. At the dissection, the bone samples were taken and the bone specimens for the histomorphometry were made. Then, bone volume, tissue volume, osteoid volume, bone surface, single ravel surface, double ravel surface, and double ravel surface area of each specimen were measured. Thereafter, bone formation rates and mineral apposition rates were analyzed. These datum of the bone histomorphometry indicated that the voluntary exercise could be effective on bone. In 1997, we continued the analisis of the bone histomorphometry. The bone formation rates and mineral apposition rates were analyzed the using several methods. In addition to this, the BMD and the bone strength were measured. All data suggested that the exercise is effective for bone formation. However, inadequate of energy intake affected negativry on bone metabolism.In 1997, we also examined the effect of the Egg-shell Ca and the Toche bark extraction on bone metabolism using the animal model of osteoporosis. The results of these studies suggested that the egg-shell Ca and the Toche bark extraction were effective for the prevention of osteoporosis.